Easily handling penicillin G acylase magnetic cross-linked enzymes aggregates: Catalytic and morphological studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Litofácies e relações estratigráficas da formação Aquidauana no nordeste da Bacia do Paraná - São Sebastião do Paraíso (MG)

The Aquidauana Formation is characterized by sandstones of variable granulation, mudstones and diamectites abundant in clay, typical colors like brick red (vermelho tijolo) of glacial, fluvial and lacustrine origin. It’s chronostratigraphic equivalent to the Itarará group from the Neo Carboniferous age, that under the exploratory view, such units represent important intervals in the basin, occurring together with them minerals as well as energy resources as petroleum, underground water and coal – what requires a great paleogeography and stratigraphy knowledge for its exploration. By gathering information from the columnar sections of the area, it was possible to characterize the sedimentary facies, the stacking pattern as well as the association. It was also made an attempt of stratigraphic correlation, which showed great difficulties since glacial environments present a great lateral discontinuity of the facies besides the complex relationship process of formation. As a result, it was obtained 8 sedimentary facies, the lateral and vertical relations and genesis process. It is proposed that the sedimentary environment in the study area is the fluvio glacial, characterized by alluvial systems formed by defrosted water which transport the sediments that are deposited in plains in front of the glacier (distal outwash). Petrographic thin section analysis showed that the transportation process was ineffective. The grains present punctual to lobular contacts, characterizing good porosity and permeability to the rock, varying these qualities according to more or less existence of matrix. The presence of Iron Oxide deposited between the recrystallization border and feldspathic mineral indicates that this rock has possibly presented a primary rubefaction, intensified by alkaline fluid percolation

Modificação superficial de nanopartículas de óxido de ferro por poli(ácido aspártico) reticulado

Pós-graduação em Química - IQ

Biocellulose-based flexible magnetic paper

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Marginal deterioration of the silicone for facial prosthesis with pigments after effect of storage period and chemical disinfection

The failure of facial prostheses is caused by limitations in the properties of existing materials, especially flexibility and durability. Therefore, this study evaluated the marginal deterioration of a silicone used for fabrication of facial prostheses (Silastic MDX4-4210, Dow Corning Corporation, Midland, MI, USA) according to the influence of artificial aging, daily disinfection, and 2 types of pigmentation. Thirty specimens were fabricated and subdivided in 6 groups: without pigmentation, pigmented with make-up powder and iron oxide, and evaluated with and without the action of the disinfectant. Analysis of marginal deterioration was performed on a scanning electron microscope (magnification, ×5000) immediately 6 months and 1 year after fabrication of specimens, following the guidelines of ASTM International. After visual analysis of the photomicrographs, it was noticed that all groups presented marginal deterioration and alterations in surface texture with time. The use of disinfection did not contribute to the marginal deterioration of polymer (silicone), regardless of the pigmentation and artificial aging.

Avaliação da promiscuidade catalítica de soroalbuminas em sínteses orgânicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparação, caracterização e estudo da eficiência na fotodegradação e adsorção de Rodamina B de heteroestruturas de TiO2/α-Fe2O3

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modificação da superfície de óxidos de ferro por dextrana derivatizada para aplicações em liberação de fármaco

Pós-graduação em Química - IQ

Modificação da superfície de óxidos de ferro por dextrana derivatizada para aplicações em liberação de fármaco

Pós-graduação em Química - IQ

Recent Advances in the Development of Magnetically Recoverable Metal Nanoparticle Catalysts

The aim of this Account is to provide an overview of our current research activities on the design and modification of superparamagnetic nanomaterials for application in the field of magnetic separation and catalysis. First, an introduction of magnetism and magnetic separation is done. Then, the synthetic strategies that have been developed for generating superparamagnetic nanoparticles spherically coated by silica and other oxides, with a focus on well characterized systems prepared by methods that generate samples of high quality and easy to scale- up, are discussed. A set of magnetically recoverable catalysts prepared in our research group by the unique combination of superparamagnetic supports and metal nanoparticles is highlighted. This Account is concluded with personal remarks and perspectives on this research field.

Magnetic nanohydrometallurgy: A promising nanotechnological approach for metal production and recovery using functionalized superparamagnetic nanoparticles

We report on a new, promising nanotechnological approach for hydrometallurgy based on recyclable, chemically functionalized superparamagnetic nanoparticles. In this process, the metal ions (e.g. Cu2+) are captured by the nanoparticles and confined at the electrode surface by means of an external magnet. Due to the pre-concentration effect the electrodeposition process is greatly improved, yielding the pure metal in a much shorter time in comparison with the conventional electrodeposition process. After the electrolysis, the magnetic nanoparticles are ready to return to the process. The proposed strategy can advantageously be incorporated in hydrometallurgy, reducing the number of steps associated with complexation, organic solvent extraction, metal release and diffusional electroprocessing, leading to a more sustainable technology. (C) 2012 Elsevier B.V. All rights reserved.

Preparation and Structural Characterization of Vulcanized Natural Rubber Nanocomposites Containing Nickel-Zinc Ferrite Nanopowders

Single-phase polycrystalline mixed nickel-zinc ferrites belonging to Ni0.5Zn0.5Fe2O4 were prepared on a nanometric scale (mean crystallite size equal to 14.7 nm) by chemical synthesis named the modified poliol method. Ferrite nanopowder was then incorporated into a natural rubber matrix producing nanocomposites. The samples were investigated by means of infrared spectroscopy, X-ray diffraction, scanning electron microscopy and magnetic measurements. The obtained results suggest that the base concentration of nickel-zinc ferrite nanoparticles inside the polymer matrix volume greatly influences the magnetic properties of nanoconnposites. A small quantity of nanoparticles, less than 10 phr, in the nanocomposite is sufficient to produce a small alteration in the semi-crystallinity of nanocomposites observed by X-ray diffraction analysis and it produces a flexible magnetic composite material with a saturation magnetization, a coercivity field and an initial magnetic permeability equal to 3.08 emu/g, 99.22 Oe and 9.42 X 10(-5) respectively.

Magnetic and optical investigation of 40SiO(2)center dot 30Na(2)O center dot 1Al(2)O(3)center dot(29-x) B2O3 center dot xFe(2)O(3) glass matrix

Samples of 40SiO(2)center dot 30Na(2)O center dot 1Al(2)O(3)center dot(29 - x)B2O3 center dot xFe(2)O(3) (mol%), with 0.0 <= x <= 17.5, were prepared by the fusion method and investigated by electron paramagnetic resonance (EPR), optical absorption (OA) and Mossbauer spectroscopy (MS). The EPR spectra of the as-synthesized samples exhibit two well-defined EPR signals around g = 4.27 and g = 2.01 and a visible EPR shoulder around g = 6.4, assigned to isolated Fe3+ ion complexes (g = 4.27 and g = 6.4) and Fe3+-based clusters (g = 2.01). Analyses of both EPR line intensity and line width support the model picture of Fe3+-based clusters built in from two sources of isolated ions, namely Fe2+ and Fe3+; the ferrous ion being used to build in iron-based clusters at lower x-content (below about x = 2.5%) whereas the ferric ion is used to build in iron-based clusters at higher x-content (above about x = 2.5%). The presence of Fe2+ ions incorporated within the glass template is supported by OA data with a strong band around 1100 nm due to the spin-allowed E-5(g)-T-5(2g) transition in an octahedral coordination with oxygen. Additionally, Mossbauer data (isomer shift and quadrupole splitting) confirm incorporation of both Fe2+ and Fe3+ ions within the template, more likely in tetrahedral-like environments. We hypothesize that ferrous ions are incorporated within the glass template as FeO4 complex resulting from replacing silicon in non-bridging oxygen (SiO3O-) sites whereas ferric ions are incorporated as FeO4 complex resulting from replacing silicon in bridging-like oxygen silicate groups (SiO4). (C) 2012 Elsevier Masson SAS. All rights reserved.

Application of magnetically induced hyperthermia in the model protozoan Crithidia fasciculata as a potential therapy against parasitic infections

Background: Magnetic hyperthermia is currently a clinical therapy approved in the European Union for treatment of tumor cells, and uses magnetic nanoparticles (MNPs) under time-varying magnetic fields (TVMFs). The same basic principle seems promising against trypanosomatids causing Chagas disease and sleeping sickness, given that the therapeutic drugs available have severe side effects and that there are drug-resistant strains. However, no applications of this strategy against protozoan-induced diseases have been reported so far. In the present study, Crithidia fasciculata, a widely used model for therapeutic strategies against pathogenic trypanosomatids, was targeted with Fe3O4 MNPs in order to provoke cell death remotely using TVMFs. Methods: Iron oxide MNPs with average diameters of approximately 30 nm were synthesized by precipitation of FeSO4 in basic medium. The MNPs were added to C. fasciculata choanomastigotes in the exponential phase and incubated overnight, removing excess MNPs using a DEAE-cellulose resin column. The amount of MNPs uploaded per cell was determined by magnetic measurement. The cells bearing MNPs were submitted to TVMFs using a homemade AC field applicator (f = 249 kHz, H = 13 kA/m), and the temperature variation during the experiments was measured. Scanning electron microscopy was used to assess morphological changes after the TVMF experiments. Cell viability was analyzed using an MTT colorimetric assay and flow cytometry. Results: MNPs were incorporated into the cells, with no noticeable cytotoxicity. When a TVMF was applied to cells bearing MNPs, massive cell death was induced via a nonapoptotic mechanism. No effects were observed by applying TVMF to control cells not loaded with MNPs. No macroscopic rise in temperature was observed in the extracellular medium during the experiments. Conclusion: As a proof of principle, these data indicate that intracellular hyperthermia is a suitable technology to induce death of protozoan parasites bearing MNPs. These findings expand the possibilities for new therapeutic strategies combating parasitic infection.

The processing of polyelectrolyte-covered magnetite nanoparticles in the form of nanostructured thin films

Magnetic nanoparticles are promising for a variety of applications, such as biomedical devices, spin electronics, magnetic data storage media, to name a few. However, these goals may only be reached if stable and organized structures are fabricated. In this article, we report on a single-step synthetic route with the coprecipitation method, in which iron oxide magnetic nanoparticles (Fe3O4 NPs) were stabilized in aqueous media using the poly(diallyldimethylammonium chloride) (PDAC) polyelectrolyte. The Fe3O4 NPs had a diameter of ca. 5 nm, according to transmission electron microscopy (TEM) images, being arranged in an inverse spinel structure typical of magnetite. An investigation with infrared spectroscopy indicated that the mechanisms of stabilization in the polymer matrix were based on the interaction between quaternary amide groups from PDAC and the nanoparticle surface. The Fe3O4-PDAC NPs exhibited considerable magnetic susceptibility, with a monotonic increase in the magnetization with decreasing temperature. These Fe3O4-PDAC NPs were immobilized in layer-by-layer (LbL) films, being alternated with layers of poly(vinylsulfonic acid) (PVS). The LbL films were much rougher than typical films made with polyelectrolytes, and Fe3O4-PDAC NPs have been responsible for the high electrocatalytic activity toward H2O2 reduction, with an overpotential shift of 0.69 V. Overall, the stability, magnetic properties and film-forming ability indicate that the Fe3O4-PDAC NPs may be used for nanoelectronics and bioelectrochemical devices requiring reversible and magnetic redox materials.